Thermostatic overload switches



May 24, 1955 w, LANDMER 2,709,208

THERMOSTATIC OVERLOAD SWITCHES Filed Feb. 16, 1953 2 Sheets-Sheet l[NVENTDR W1 LLL M [3. LANDWIER BY WW ATTUENIY y 1955 w. G. LANDWIER 2%THERMOSTATIC OVERLOAD SWITCHES Filed Feb. 16, 1953 2 Sheets-Sheet 2 IN VEN TOR.

WILLIAM GLANDWIER ATTUENEY nited States Patent TJERh EQEETATIC OVERLOADSWITCHES Wiiiiam G. Landwier, Fayetteville, N. Y., assignor to EasyWashing Machine Corporation, Syracuse, N. Y., a corporation of DelawareApplication February 16, 1953, Serial No. 336,9?9

3 Claims. (Cl. 200116) This invention relates to thermostatic overloadswitches, and more particularly to those adapted for thermostatic andmanual operation and use on domestic appliances.

The present invention is directed toward providing a rugged switchcomposed of few parts, free of pivots, certain of operation, readilyassembled and low in cost of manufacture. The invention further isdirected to providing a switch having a single manual operating memberadapted to close or open the contacts, such switch having a thermostaticoverload current-sensitive lock, so disposed in relation to theoperating member as to be mechanically or thermally actuated to open thecontacts.

The above and other novel features of the invention will appear morefully hereinafter from the following detailed description when taken inconjunction with the accompanying drawings. It is expressly understoodthat the drawings are employed for purposes of illustration only and arenot designed as a definition of the limits of the invention, referencebeing had for this purpose to the appended claims.

in the drawings, wherein like reference characters indicate like parts:

Figure 1 is a side elevation of the internal mechanism, the casing beingbroken away;

Figure 2 is a horizontal section taken substantially on the line 2-2 ofFigure 1;

Figure 3 is a transverse section taken on the line 33 of Figure 2;

Figure 4 is a diagrammatic perspective view of the moving parts with thepush member 46 in exploded relation; and

Figures 5, 6 and 7 are diagrammatic figures showing stages in theoperation of the switch.

In the drawings, there is shown a rectangular base plate ill formed ofinsulating material secured to a boxlike housing member 12, preferablyof insulating material, such members being held together by fasteningscrews 14 and 16. The base plate is seated in an offset l8 extendingaround the inside periphery of the open end of the casing. Mounted onthe base plate are a con ductive terminal plate 20 centrally located,and at either end, a conductive terminal bracket 24 and a conductivecontact supporting bracket 26. The terminal plate 20 is provided with arelatively stationary conductive contact 28 supported upon a U-shapedresilient conductive mounting member 30. The contact bracket 26 has anintegral upstanding support post 32 to which is secured a resilientconductive leaf 34 having aflixed thereto a contact 36 adapted to engagecontact 28. The leaf 34 is stiffened along one edge by a flange 40, suchflange terminating as at 42 short of the end of the leaf secured to thesupport post 32.

The leaf 34 is notched along one edge as at 44, and is adapted to beengaged by a manual push member 4-6 H slidingly mounted in the top 48 ofthe casing 12. The push member is formed of plastic or other suitablenonconductive material, and may be substantially square in crosssection, and is provided with a rounded end 50 within the casing, suchend being adapted to engage the leaf 34 to move the contact 36downwardly. Projecting beyond the rounded end 50 is an offset fingernon-conductive extension 62 which extends through the notch 44 and isadapted to engage the upper horizontal end 54 of the U-member 30,supporting contact 28. The finger 52 is of suificient length that upondepressing the push member 46, the finger engages the upper end 54 ofthe resilient contact member 30 after the end 50 engages the leaf 34,but before the leaf 34 is depressed sufficiently to close the contacts36 and 28. Thus, the downward movement of the push member 46 does notclose the contacts 28 and 36. A resilient leaf member 56 secured to theunder side of the top wall 48 of the casing 12 extends across one sideof the push member 46 and through an inclined notch 58 in the side wallof the push member 46. Such leaf spring is adapted to normally returnthe push member to the position shown in Figure l.

The terminal bracket 24 is provided with an upstanding integralconductive post 60 While the post 32 is provided with a longitudinallyextending conductive bracket portion 62. Extending between the post 60and bracket 62 is a resilient conductive strap assembly composed of abimetallic heat-sensitive member 64 and a conductive U- spring 66, thebimetallic member and U-spring being secured together as at 68. The endof the ti-spring 66 is secured to the post 60 as at 70, while thebimetallic strap is supported at one end thereof upon the bracket 62..The bimetallic strap at its other end is notched as at '72 and the endportion 74 thereof deformed so as to lie in a plane forming an acuteangle with the plane of the supported end of the bimetallic strap. Theinclined portion 74 forms a cam and the lower edge 76 thereof is adaptedto engage the tip end 78 of the leaf 34 to form a lock when such leaf ismoved downwardly by operation of the non-conductive push member beyondthe lower edge 76, it being understood that through such action, thebimetallic strap is cammed laterally away from the leaf as the tip end78 is moved downwardly past the locking edge 76. It will be seen thatwhen the leaf member bearing contact 36 is depressed by manipulation ofthe push member 46 to the locking position and s thereafter the pushmember is released so as to return to the position shown in Figure 1,the finger 52 permits the return of the contact bearing portion 54 ofthe spring member 30, whereby the contacts 28 and 36 engage to close acircuit.

it will appear that the bimetallic member 64 is in a series circuit fromthe terminal bracket 24 to the supporting bracket 26 and through thecontact leaf 34, contacts 36 and 23 and resilient member 3'3 to theterminal plate Ztl. It will also be understood that the bimetallic metalstrap 64 is so constituted that upon a temperature rise, such strap willwarp in a direction away from the leaf 34, that is, the surface of thebimetallic strap presented toward the leaf 34 will be rendered convex invarying degrees in accordance with the temperature generated therein.Thus, a current passing through the bimetallic strap 64 will effect atemperature rise therein, and if too great over a period of time, causethe bimetallic member and particularly the lock edge 76 at the extremeend thereof, to move away from locking tip '78 of the leaf member 34, soas to release the leaf 34 to open the contacts 36 and 23. In Figure 5,the switch parts are shown with the push member depressed. The finger 52has engaged the upper end 54 of the contact member or leaf 3t preventingengagement of the contacts. The leaf 34 has been caused to pass theinclined portion 74 of the bimetallic leaf. In Figure 6, the push memberhas been allowed to return, whereupon the leaf arouses 34 is held by theinclined portion 74, so that the contacts close. In Figure 7, the pushmember has been retracted so that the cam 80 (see Figure 4) has actedupon the inclined recess 82 to swing the bimetallic member away from theleaf 34, allowing leaf 34 to swing upwardly to open the contacts. Anyheating of the bimetallic member due to overload has a similar efiect,causing the inclined portion "74 thereof to swing so as to free the leaf34, to open the contacts.

Manual means are provided for opening the contacts 28 and 36 through amovement of the push member 46 outwardly. The finger 52 is provided onits outer face' with a camming surface 84 which is adapted to engage andride against an inclined surface 32 formed in and along the lower edgeof the bimetallic strap 6-4. Thus, upon moving the push member 46outwardly from the position shown in Figure l a slight distance, thebimetallic strap is cammed outwardly away from the leaf 34 whereby thelocking edge 76 is moving laterally out of engagement with the lockingtip 73 at the end of the leaf 34.

The housing 12 is provided with a non-conductive projection 84 which maybe molded integral therewith, which projection is adapted to engage theouter end of the leaf 3 to limit its upward movement, whereby suchmember may have a pre-stressed resiliency in the portion thereofadjacent the end fixed to the post 32. The terminal plate 26, brackets24 and 26 may be secured in any suitable manner to the insulated plate ias by rivets 86. The other various members may be secured as by spotwelds 88. The push member 46 is provided with a knob 96 having suitablerecesses for receiving the end of the push member 46, such knob beingheld on the end by any suitable means such as a screw )2.

While a single embodiment of the invention has been illustrated anddescribed, it is to be understood that the invention is not limitedthereto. As various changes the construction and arrangement may be madewithout departing from the spirit of the invention, as will be apparentto those skilled in the art, reference will be had to the appendedclaims for a definition of the limits of the invention.

What is claimed is:

1. In an overload cutout switch, a non-conductive base, a conductiveterminal block mounted thereon centrally thereof, a relativelystationary contact mounted on said block and facing away from said base,a conductive bracket at each end of said base, a resilient conductivecontact leaf affixed at one end to one of said brackets,

and projecting over said stationary contact, said leaf 5.

having a movable contact facing said stationary contact, and beingbiased to normally hold said contacts out of engagement with oneanother, a guideway mounted on said base and extending perpendicular tosaid base and in substantial alignment with the contact end of saidleaf, a manual plunger slidably mounted in said guide way and adapted toengage said leaf upon downward movement thereof, a resilient conductivestrap connecting said brackets and arranged laterally of and adjacentsaid leaf, and adapted for lateral movement with respect to said leaf,cam locking means on said leaf and strap adapted to hold said leaf incontact closed position, when moved to contact closed position by saidplunger, a bimetal resistance section in said strap for moving said lockaway from said leaf to open said contacts upon the heating of saidsection to a predetermined temperature, and non-conductive cam means onsaid plunger adapted upon upward movement thereof to engage said strapto move said lock away from said leaf to open said contacts.

2. In an overload cutout switch, a non-conductive base,

a conductive terminal block mounted thereon centrally thereof, arelatively stationary contact mounted on said block and facing away fromsaid base, said contact being resiliently movable toward and away fromsaid base, a bracket at each end of said base, a resilient conductivecontact leaf afiixed at one end to one of said brackets, and projectingover said stationary contact, said leaf having a movable contact facingsaid stationary contact, and being biased to normally hold said contactsout of engagement with one another, a housing for said contacts mountedon said base, said housing having a guideway extending perpendicular tosaid base and in substantial alignment with the contact end of saidleaf, a manual plunger slidably mounted in said guideway and adapted toengage said leaf upon downward movement thereof, a resilient conductivestrap connecting said brackets and arranged laterally of and adjacentsaid leaf, and adapted for lateral movement with respect to said leaf,cam locking means on said leaf and strap adapted to hold said leaf incontact closed position, when moved to contact closed position by saidplunger, a bimetal resistance section in said strap for moving said lockaway from said leaf to open said contacts upon the heating of saidsection to a predetermined temperature, and non-conductive cam means onsaid plunger adapted upon upward movement thereof to engage said strapto move said lock away from said leaf to open said contacts.

3. In an overload cutout switch, a non-conductive base, a conductiveterminal block mounted thereon centrally thereof, a relativelystationary lower contact mounted on one end of a resilient U-striphaving its other end secured to said block, said contact facing awayfrom said base, said contact being resiliently movable toward and awayfrom said base, a conductive bracket at each end of said base, aresilient conductive contact leaf affixed at one end to one of saidbrackets, and projecting over said stationary contact, said leaf havinga movable contact facing said stationary contact, and being biased tonormally hold said contacts out of engagement with one another, ahousing for said contacts mounted on said base, said housing having aguideway extending perpendicular to said base and in substantialalignment with the contact end of said leaf, a manual plunger slidablymounted in said guideway and adapted to engage said leaf upon downwardmovement thereof, and having a non-conductive finger projecting beyondthe end thereof for engaging said resilient U-strip to move said lowercontact to prevent engagement with said leaf contact while said plungeris depressed, a resilient conductive strap connecting said brackets andarranged laterally of and adjacent said leaf, and adapted for lateralmovement with respect to said leaf, cam locking means on said leaf andstrap adapted to hold said leaf in contact closed position, when movedto contact closed position by said plunger, said resilient U-membermoving said lower contact into contact engagement with said leaf contactwhen locked, and said plunger is released, a bimetal resistance sectionin said strap for moving said lock away from said leaf to open saidcontacts upon the heating of said section to a predeterminedtemperature, and non-conductive cam means on said plunger adapted iponupward movement thereof to engage said strap to move said lock away fromsaid leaf to open said contacts.

References Cited in the file of this patent UNITED STATES PATENTS2,458,807 Tucker Jan. 11, 1949 2,476,648 Zeller July 19, 1949 2,563,103Davis Aug. 7, 1951 2,518,741 Alexander Aug. 15, 1950

